In the pumping of oil wells, virtually all of the well fluid that is pumped includes a quantity of natural gas in solution. For example, the fluid medium pumped may be oil or a mixture of oil and water and will typically include a quantity of gas in solution. During a typical pumping operation, the fluid medium of the well undergoes substantial pressure changes, and these pressure changes tend to allow the gas in solution to become liberated from the liquid constituents of the fluid medium, and the liberated gas may interfere with pumping operations. For example, the fluid medium of a well prior to entering the tubing string or pumping chamber of the well is subjected to a pressure known as the "bottom hole pressure." This bottom hole pressure relates to the inherent pressure of the production formation and to the hydrostatic head of the fluid medium within the well bore. In typical oil wells that require pumping, there is provided a pair of spaced ball seat valves with the pump piston being positioned above the uppermost ball seat valve. As the pump piston moves downwardly, the ball seat valve will become seated, and fluid between the piston and the uppermost ball seat valve will become displaced past the pump piston mechanism. Upon upward movement of the pump piston mechanism, the previously displaced fluid will be moved upwardly for production, and a vacuum condition will be developed within the pumping chamber between the piston and the uppermost ball seat valve. Responsive to this vacuum condition, the ball seat valve will become unseated, and additional fluid medium will flow past the ball seat valve and will enter the pumping chamber, whereupon the pumping cycle may be repeated. As the pump piston moves downwardly, the fluid medium within the pumping chamber is subjected to pressurization for purpose of fluid displacement. As the piston mechanism moves upwardly, however, this fluid medium is subjected to a condition of partial vacuum. Natural gas entrained within the fluid medium tends to become liberated during the partial vacuum condition of the upstroke of the piston. Any natural gas accumulated within the pumping chamber is simply compressed during pumping movement and may interfere with efficient transfer of fluid between the pumping chamber and the tubing. At such time that liquid and gas pressure above the uppermost ball and seat valve of the pumping mechanism equalizes or is greater than the pressure that is developed in the pumping barrel during pumping operations, the piston element will simply cycle in its normal manner, but fluid transfer will not occur because the piston movement merely causes compression and expansion of the gas within the pumping chamber. This condition is known as "gas-lock" in the industry and is, of course, the subject of much concern to the industry from the standpoint of losses in production.
Where the pumping mechanism of the well includes a stationary valve mechanism having a ball and seat with a traveling valve mechanism also having a ball and seat that is movable relative to the stationary valve mechanism. The variable volume between the ball and seat mechanisms of the stationary and traveling valve devices constitutes the pumping chamber. A condition of gas-lock will occur when an excessive amount of gas collects within the pumping chamber and the pressure developed by the hydrostatic head of liquid above the ball and seat mechanism of the traveling valve is equal to or greater than the pressure of the compressed gas within the pumping chamber in the compression stroke, and when the pressure within the pumping chamber during the vacuum stroke is equal to the bottom hole pressure of the well. It is of course very desirable to provide a traveling oil pump valve mechanism that is capable of efficiently lifting well fluid, including oil, to the surface for production and which is also effective to prevent the development of a gas-lock condition during pumping. Accordingly, it is a primary feature of the present invention to provide a novel traveling oil pump valve mechanism that serves as the traveling valve mechanism of a spaced valve pumping system and which automatically provides for venting liberated gas into the tubing string for production along with the liquid medium that is pumped from the well.
It is also an important feature of the present invention to provide a novel traveling oil pump valve mechanism incorporating very few parts that are exposed to wear during pumping operations, thereby promoting the effective service life of the pumping mechanism.
Among the several features of the present invention is noted the contemplation of a novel traveling oil pump valve mechanism that is very simply assembled and disassembled and may be repaired quite easily and inexpensively.
It is also a feature of the present invention to provide a novel traveling oil pump valve mechanism that is of simple nature, is low in cost and reliable in use.